A 71-year-old man fighting for life after assault at Wyndham Vale 7/11

A man is fighting for life after what appeared to be a dispute at the bowser of a 7/11 in Melbourne's southwest turned violent this morning.

The victim, a 71-year-old man, was taken to the Royal Melbourne Hospital in a critical condition after an alleged altercation between two men at the 7/11 on the corner of Ballan Road and McGrath Road in Wyndham Vale around 11.45am.

Another man, 35, was arrested at the scene and remains in police custody.